Step-down conversion circuit assembly and electronic device

1. A step-down conversion circuit assembly, comprising: a box body having a plurality of side walls, wherein the plurality of side walls define an enclosed accommodating space, and the box body defines an air outlet on one of the plurality of side walls; a step-down conversion circuit disposed in the accommodating space of the box body; a heat dissipation element comprising a first heat dissipation sub-element attached to a surface of the step-down conversion circuit and a second heat dissipation sub-element, wherein the second heat dissipation sub-element smoothly extends from an edge of the first heat dissipation sub-element and extends to contact the side wall of the box body defining the air outlet; and a fan disposed between the step-down conversion circuit and the air outlet and below the heat dissipation element, and configured to enable the heat in the accommodating space to exit from the air outlet.

2. The step-down conversion circuit assembly of claim 1 , wherein the heat dissipation element is attached to the step-down conversion circuit through a thermally conductive silica gel.

3. The step-down conversion circuit assembly of claim 1 , wherein: the step-down conversion circuit has a first surface and a second surface opposite the first surface; and the first heat dissipation sub-element is attached to the first surface and the heat dissipation element further comprises a third heat dissipation sub-element attached to the second surface.

4. The step-down conversion circuit assembly of claim 1 , wherein the heat dissipation element is attached to a surface of the step-down conversion circuit and has a larger area than the surface.

5. The step-down conversion circuit assembly of claim 4 , wherein the heat dissipation element is perpendicular to the side wall where the air outlet locates.

6. The step-down conversion circuit assembly of claim 4 , wherein: the box body has an inner wall opposite the air outlet; the step-down conversion circuit is disposed at the inner wall; and the heat dissipation element comprises an extension portion extending beyond the step-down conversion circuit, wherein the extension portion is disposed between the step-down conversion circuit and the air outlet.

7. The step-down conversion circuit assembly of claim 4 , wherein the first heat dissipation sub-element is parallel to the surface of the step-down conversion circuit, the surface is perpendicular to the side wall where the air outlet locates, and the second heat dissipation sub-element is disposed between the air outlet and the step-down conversion circuit.

8. The step-down conversion circuit assembly of claim 7 , wherein the second heat dissipation sub-element defines a plurality of notches on a middle of the second heat dissipation sub-element, wherein the accommodating space is in communication with the air outlet through the plurality of notches.

9. The step-down conversion circuit assembly of claim 8 , wherein the second heat dissipation sub-element comprises a plurality of bosses, wherein each two bosses define one notch.

10. The step-down conversion circuit assembly of claim 1 , wherein the heat dissipation element comprises an extension portion extending beyond the step-down conversion circuit, wherein the extension portion has a second surface away from the step-down conversion circuit and a first surface opposite the second surface, wherein the first surface and the second surface are provided with a plurality of bosses.

11. The step-down conversion circuit assembly of claim 1 , wherein the plurality of side walls of the box body are made of heat insulation materials.

12. An electronic device comprising: a step-down conversion circuit assembly comprising: a box body having a plurality of side walls, wherein the plurality of side walls define an enclosed accommodating space, and the box body defines an air outlet on one of the plurality of side walls; a step-down conversion circuit disposed in the accommodating space of the box body; a heat dissipation element comprising a first heat dissipation sub-element attached to a surface of the step-down conversion circuit and a second heat dissipation sub-element, wherein the second heat dissipation sub-element smoothly extends from an edge of the first heat dissipation sub-element and extends to contact the side wall of the box body defining the air outlet; and a fan disposed between the step-down conversion circuit and the air outlet and below the heat dissipation element, and configured to enable the heat in the accommodating space to exit from the air outlet.

13. The electronic device of claim 12 further comprising a wireless receiving circuit, a battery, and a second control module, wherein: the step-down conversion circuit assembly is electrically coupled with the wireless receiving circuit and the battery; the wireless receiving circuit is configured to receive energy transmitted by a wireless transmitting circuit and convert the energy into electric energy; the step-down conversion circuit assembly is configured to step down the electric energy converted by the wireless receiving circuit for charging the battery; and the second control module is electrically coupled with the wireless receiving circuit and the step-down conversion circuit assembly and configured to switch on or switch off the step-down conversion circuit assembly and the wireless receiving circuit.

14. The electronic device of claim 12 further comprising a wireless communication module, wherein the wireless communication module is configured to conduct bidirectional communication with a wireless charging device to control output power of the wireless charging device.

15. The electronic device of claim 12 , wherein: the electronic device supports a first charging mode and a second charging mode, wherein a charging speed of the electronic device in the second charging mode is higher than that in the first charging mode; and the electronic device further comprises a wireless communication module, wherein the wireless communication module is configured to conduct bidirectional communication with a wireless charging device to control output power of the wireless charging device in the second charging mode.

16. The electronic device of claim 12 further comprising a wireless communication module, wherein the wireless communication module is configured to transmit at least one of data in universal serial bus (USB) protocol format, data in display port (DP) protocol format, or data in mobile high-definition link (MHL) protocol format.

17. The electronic device of claim 12 further comprising a wireless communication module, wherein the wireless communication module is configured to conduct bidirectional communication with a wireless charging device to negotiate a charging mode of the wireless charging device.

18. The electronic device of claim 12 , wherein: the step-down conversion circuit assembly is disposed inside the electronic device; the electronic device defines a through hole on an edge of the electronic device; and the air outlet of the step-down conversion circuit assembly communicates with the through hole.

19. The electronic device of claim 18 , wherein the electronic device has a first side, wherein the through hole is defined on the first side, and the step-down conversion circuit assembly is adjacent to the first side.

20. A step-down conversion circuit assembly, comprising: a box body defining an air outlet extending through a side wall of the box body; a step-down conversion circuit disposed in the box body; a heat dissipation element comprising a first heat dissipation sub-element attached to a surface of the step-down conversion circuit and a second heat dissipation sub-element, wherein the second heat dissipation sub-element smoothly extends from an edge of the first heat dissipation sub-element and extends to contact the side wall of the box body defining the air outlet; and a fan disposed between the step-down conversion circuit and the air outlet and below the heat dissipation element, and configured to enable the heat in the box to exit from the air outlet.